Biotropica最新文献

Human-induced changes in landscape composition and configuration have a significant impact on species, including bats. Some bat species may be affected, while others can take advantage of the new available resources. In this study, we analyzed the response of the abundance, effective number of species, and dominance of bats to landscape composition and configuration, as well as a set of environmental factors in the municipalities of Santa María Huatulco and San Miguel Lachiguiri, Oaxaca, southeastern Mexico. We used a multimodel inference statistical approach to identify those variables explaining bat abundance and diversity of bats captured with mist nets. A 5.5 km radius circular landscape was established from an urban center in Huatulco and Lachiguiri. Within these areas, 1 km radius units (nine in Huatulco and eight in Lachiguiri) varying in the proportion of tropical forest, urban area, agriculture, and grassland were established. From 2020 to 2022, we captured 477 bats (58.49% in Huatulco and 41.51% in Lachiguiri) belonging to 21 species. The most abundant species were Artibeus lituratus (33.1% of the captures) and Artibeus jamaicensis (21.4%). The diversity of trophic guilds was twice as high in Lachiguiri (n = 6) compared to Huatulco (n = 3). In general, the variables that influenced the abundance and diversity of bats were the proportion of the landscape covered by human settlements and by deciduous forest, the fractal dimension index, temperature, seasonality, and distance to urban centers. Our results show that changes in landscapes, as well as temperature, play an important role in bat diversity in the study area. Conservation actions should be aimed at conserving all elements of the landscape that allow increasing the availability of resources (i.e., food, roosts) and, with it, the diversity and abundance of neotropical bats.

Mutualistic species often must survive periods of their development without their mutualist partner, but we lack a clear understanding of the ecological mechanisms that maintain mutualisms despite these gaps in partnership. In ant-plant protection mutualisms, plants house ant colonies that deter herbivores. Yet juvenile ant-plants often lack symbiotic ant colonies and must withstand herbivory pressure until they are colonized by ants. A sapling's ability to host ants or to employ alternative direct defenses, such as leaf secondary metabolites, may depend on access to key resources, like light, soil nutrients, and water. Alternatively, juvenile ant-plants may receive biotic protection at little resource cost from generalist predators, such as spiders. We examined whether juvenile Cecropia trees maintained leaf defenses, and whether sapling ant and chemical defenses were associated with the sapling's access to resources. We surveyed three species of naturally occurring juvenile Cecropia trees across a rainfall gradient in northwest Costa Rica. We found that both ant defense and chemical defense were regulated by the availability of light, soil fertility, and water in Cecropia saplings. Rather than trade off, larger saplings and saplings with more resources were more likely to invest in both defense strategies, whereas smaller saplings and saplings with fewer resources appeared to have little leaf defense. We also found that although spiders were common on such resource-poor, undefended saplings, spiders did not reduce herbivory. This study highlights the importance of resource availability in determining the performance of ant-plants during early ontogenetic stages.

In mimicry, a species signals a fitness cost or benefit to a receiver by resemblance to another model species. While ants are among the most frequent models, few cases of ant mimicry are known in stink bugs (Pentatomidae). Here, using a geometric morphometric analysis, we propose that Rio nymphs might mimic Cephalotes ants.

South Asia, renowned for its rich biological heritage, is home to a quarter of the global human population and has been experiencing unprecedented biodiversity loss. Anthropogenic pressures are expected to rise in the coming decades, and how governance structures respond to them will be instrumental in preserving this biodiversity. In this paper, we provide an overview of the different conservation paradigms across South Asia and discuss how these can be strengthened. Nationwide networks of Protected Areas are the principal institutional tools wherein the State delineates landscapes for biodiversity conservation and denies or restricts people's rights to access space and resources. Since the 1970s, communities have partnered with the State and have also been involved in conservation initiatives by themselves. While State-led conservation has been invaluable in safeguarding biodiversity, it is exclusionary in terms of social justice and habitat heterogeneity. Conservation under State-community partnerships is inclusive in theory, but intrinsic power asymmetry is a limitation. Even completely community-driven biodiversity governance is stifled by inequity in access to resources. Moreover, these initiatives are usually too restricted in geographical scope to support viable populations of species and often have a lack of clarity regarding governance structures and monitoring. We suggest (a) implementing landscape-level conservation, (b) ensuring ecosystem representativeness, (c) providing further autonomy to local communities, (d) ensuring clarity on rules and regulations regarding decision-making authority and rights of access and benefit-sharing, and (e) multilateral collaborations across nations in the region to make conservation governance more effective in safeguarding both biodiversity and human well-being.

We report the first case of fluorescence in four species of terrestrial and freshwater crabs from Sarawak, Borneo. We observed blue fluorescence in all the individuals examined. This study provides detailed descriptions of the fluorescence characteristics across different species contributing to understanding this phenomenon in Decapoda.

Analyses of the variation in the abortion rate and mass of seeds of tropical trees are scarce, despite their importance in modulating seed production, plant recruitment, and herbivore foraging patterns. We studied these reproductive processes in a tropical dry forest tree species. We studied the patterns of intrafruit abortion and seed mass in fruits of the Guanacaste tree, Enterolobium cyclocarpum, in samples of trees from 5 populations in Mexico and Costa Rica. We analyzed the effects of developmental phase, fruit and maternal tree effects, and seed position within the fruit on the abortion rate and mass of seeds from mature and immature fruits. Naturally pollinated flowers were studied to determine the patterns of ovule fertilization within the ovaries. Overdispersion of the abortion rate per fruit within trees and a higher frequency of abortions in the extreme positions of the fruit were common patterns in all populations. These patterns were observed from the beginning of fruit formation. Ovules in the stylar position do not have higher survival rates, despite their precedence in fertilization. A negative relationship was found between abortion events and seed mass. Fruit-specific fertilization and developmental conditions seem to be the main factors driving the fruit abortion rate and seed mass, causing high variability in seed survival and mass within maternal trees. The correlation between the fruit abortion rate and seed mass may be related to the capacity of the fruit to drain maternal resources. These patterns are common to all studied Guanacaste tree populations.

Mineral licks are critical resources for herbivores in Amazonia and other tropical regions which may be deficient in dietary minerals or consuming alkaloid-laced leaves which may cause gastrointestinal issues. However, mineral licks are also important locations for predators, including human hunters. Animals visiting mineral licks must balance the benefits of relief of physiological stressors with the risk of predation, and they may employ behavioral adaptations to do so. We used camera trap data on six large-bodied mammal species at 52 mineral licks in the same watershed in the Peruvian Amazon to assess how mineral licks contribute to visiting species' perception of risk. We tested the effects of a range of covariates including direct and indirect measures of risk, habitat characteristics, and soil properties on visit duration, a behavioral adaptation species may use to mitigate risk, in a generalized linear mixed-effects modeling framework. Tapirs, collared peccaries, and paca minimized visit duration in risky licks, while howler monkeys, red brocket deer, and black agoutis had higher visit duration in risky licks, potentially due to increased vigilance and reduced feeding efficiency. The strong relationships between risk and behavior across species demonstrates the ecological value of mineral licks for both predators and prey, as prey must seek mineral licks but at great cost. Conserving mineral licks in landscapes may be a critical component to the conservation of both herbivores and carnivores in Amazonia, and for food security of local people.